Safety system for a clamping tool

ABSTRACT

The present invention relates to a safety system for a gripping device comprising:
         a clamping tool having a body,   at least one bore through the body of the clamping tool,   at least one elongated connecting element extending through the bore, and   withholding means arranged to couple the connecting element to the clamping tool body at two different positions of the bore separated from each other.
 
The invention also relates to a corresponding safety arrangement for a gripping device.

TECHNICAL FIELD

The present invention relates to a safety system for a clamping toolsuitable for clamping drill pipes and casings during drillingoperations.

BACKGROUND ART

In the construction of oil or gas wells wrench assemblies are often usedfor making or breaking threaded joints between successive tubingelements (drill pipes) that make-up the continuous tubing stringextending through a well bore into the underground deposits. Whenmaking/breaking of pipe joints, extremely large forces (i.e. hightorques) are involved, and accidental breakage of tools/components usedduring operation could seriously injure personnel and cause harm toexpensive equipment.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to solve or at least minimisethe above mentioned problem.

This object is achieved essentially by means of a system as specified inappended claim 1. The object is also achieved by means of a safetyarrangement according to the appended claims.

It is understood that the herein presented advantages relates to bothsaid system and arrangement, even when referring only to “safetysystem”.

Thanks to the system according to the invention there is achieved atleast the advantage that in case of accidental breaking and/or crackingof the clamping tool body during operational use, said connectingelement will keep any loose parts together, preventing them from gettingejected causing damage to surrounding persons and/or equipment. Thussaid system contributes to improved safety during drilling operations.

Further advantageous embodiments of the system are specified in thedependent claims.

According to one embodiment said bore is a through bore extendingthrough the body of the clamping tool. In this embodiment the elongatedconnecting element is extending through the bore and is coupled to theclamping tool body by means of withholding means. Said withholding meansare arranged to couple the elongated connecting element to the clampingtool body at two different positions of the bore which are separatedfrom each other, preferably with majority (at least 50%) of the clampingtool body in between them, so that the connecting element is withheldinside the bore. Preferably the withholding means are arranged towithhold the connecting means at two positions located at the respectivetwo end portions of the bore. Preferably, the end portions of theconnecting element are positioned close to the respective orifice of thethrough bore so that the connecting element is kept in place by thewithholding means at each of its respective end portions. This leads toa particularly strong and reliable construction where the risk ofbreakage of the connecting element and/or the withholding means isminimised. Thus, in case the clamping tool would accidentally burst,e.g. during drilling operation, any loose parts of the tool are stillkept together by the safety system/arrangement where the combination ofwithholding means and connecting element positioned in said boreprovides a very strong safety connection.

Moreover, thanks to that the connecting element is shielded inside thebore it will not eject or get thrown away in the unlikely event ofbreakage/unfastening of the withholding means.

According to another embodiment, the through bore comprises two outerfirst portions (preferably one outer portion at each of its outeropenings) having a first diameter and a middle second portion having asecond diameter, where the first diameter is larger than the seconddiameter. Further, the withholding means has a body which comprises atleast one cross-section which is larger than the diameter of the middlesecond portion of the bore. Preferably, said withholding means arepositioned at each of the two outer first portions of the through borein such a way that they are prevented from entering the middle secondportion of the bore by means of positioning the cross-section which islarger than the diameter of the middle second portion of the bore insuch a way that it stops the withholding means from entering the middlesecond portion of the bore.

According to yet another aspect the system according to the inventioncomprises a shock absorbing component arranged adjacent to thewithholding means. Preferably the shock absorbing component is arrangedat the outer first portions of the bore, located in between the middlesecond portion of the bore and the withholding means. Hereby there isprovided a shock absorption in case any loose parts of the clamping toolwould move/get ejected as a consequence of sudden bursting/breaking.Such absorption of kinetic energy is advantageous for damage reductionif the clamping tool would break, and thus provides a further safetyfunction of the system. Said shock absorbing component also protects theconnecting element reducing the risk that the connecting element and/orthe coupling between the withholding means and the connecting elementwould break. Thus, in addition to the aspects previously presented, theobject of increasing safety during making/breaking of joints betweensuccessive tubing elements can also be achieved by use of an energyabsorbing arrangement comprising an elongated connecting element whichat each end portion is coupled to a withholding means, and wherein ashock absorbing component is arranged adjacent to said withholding meansat each end portion of the elongated connecting element. The shockabsorbing component arranged together with the elongated elementprovides synergistic effects for improved security when used in a safetysystem for a gripping device: the elongated element provides a retainingfunction when coupled to the gripping device and the shock absorbingcomponent in its turn reduces the risk that the couple between theelongated element and the gripping device break. Thus, when combined theshock absorbing component and the elongated element leads to increasedsafety and to minimized risk that pieces of a broken gripping devicewould get ejected in case of breakage of gripping equipment.

BRIEF DESCRIPTION OF THE FIGURES

The invention may be better understood by referring to the followingfigures. In the figures, like reference numerals designate correspondingparts throughout the different views.

FIG. 1 illustrates a perspective view of an example of an implementationof an automatically adjustable gripper device gripping a pipe section,

FIG. 2 illustrates a perspective view of a clamping tool according toone embodiment of the invention,

FIG. 3A illustrates a side view of the clamping tool seen in FIG. 2,

FIG. 3B is a cross-sectional view of the clamping tool of FIG. 3A takenalong line IIIB-IIIB,

FIG. 3C is a detail view according to IIIC in FIG. 3B

FIG. 4 illustrates a side view of a connecting element according to oneembodiment of the invention,

FIG. 5 illustrates a side view of a withholding means according to oneembodiment of the invention,

FIG. 6A illustrates a perspective, partially transparent, view of acracked clamping tool according to one embodiment of the invention,

FIG. 6B illustrates a frontal view of the clamping tool seen in FIG. 6A,

FIG. 7A illustrates a top view of the clamping tool seen in FIG. 6A, and

FIG. 7B is a cross-sectional view of the clamping tool of FIG. 7A, takenalong line VIIB-VIIB.

DETAILED DESCRIPTION

The foregoing aspects and many of the advantages of this invention willbecome better understood by means of the following detailed description,when taken in conjunction with the accompanying figures. Further, thedescription, and the examples contained therein, are provided for thepurpose of describing and illustrating certain embodiments of theinvention only and are not intended to limit the scope of the inventionin any way.

Referring firstly to FIG. 1 there is shown in a schematic way a portionof a wrenching equipment 1, herein also referred to as a “gripper” or“gripping device 1”, intended for making or breaking threaded jointsbetween successive tubing/pipe elements (e.g. drill pipes).

As shown in FIG. 1 the gripping device 1 is arranged with twoarticulated gripping arms 101 embracing a pipe section 11. The pipe 11can be for example a drill pipe for a drill string or a borehole casing,and two grippers 1 can be used to grip two pipe section 11 to connect ordisconnect successive pipes at complementary threads in the pipes.

The gripper 1 according to the invention is suitable for use inconjunction with drilling in the ground or seabed for assembling anddisassembling drill strings and borehole casings comprising a pluralityof straight pipes connected end to end. However, it is to be understoodthat the arrangement according to the invention is not necessarilylimited to equipment for oil/gas industry but that the safetyarrangement according to the invention may be used for any grippingdevice intended for connecting and/or disconnecting pipe sections.

As seen in FIG. 1 each arm 101 of said gripper 1 is equipped with aclamping tool 2, herein also referred to as a “clamping jaw” or “holdingdevice”. Preferably the clamping tool 2 comprises a body in the form ofa casted item with a single solid body preferably made of metal. Eachclamping tool 2 holds at least one releasably attached pipe contactingelement 3 which is arranged to be brought into direct contact with thepipe section 11 during gripping of the pipe section forconnection/disconnection operation as previously described. A pipecontacting element 3 is herein also referred to as a die. When thegripper 1 grips a pipe 11, the pipe contacting elements 3 are preferablyin direct contact with the pipe 11.

The gripping arms 101 are connected with an articulated joint 102.Preferably the gripper 1 comprises a drive in the form of a hydraulicactuator (now shown). By means of the hydraulic actuator, the gripper 1can rotate one of the gripping arms 101, in relation to the othergripping arm 101, about the articulated joint 102. Thereby, the gripper1 is adapted to move the gripping arms 101 in relation to each other soas to grip a pipe P, whereby the dies 3 are in contact with the pipe, orso as to release to the pipe.

In FIG. 1 each clamping tool 2 holds two dies 3. This is seen moreclearly for example in FIG. 2, which shows a perspective view of aclamping tool 2 provided with a pair of dies 3. Herein is also seen thatthe dies 3 have a surface presenting a curvature that is supposed to beidentical to the curvature of the pipe 11 to be gripped. By switchingbetween dies 3 having different dimensions/curvatures the gripper 1 iseasily adapted to various sizes of pipe sections (pipes with differentdiameters) whereby connection/disconnection operations can besignificantly improved. The curved surface of the dies 3 have, as can beseen in some of the following figures, small ridges to increase thefriction or the grip between the dies and the pipe 11.

Using a die 3 having a dimension that does not match with the diameterof the pipe 11 to be gripped would lead to mechanical strain in the bodyof the clamping tool 2 holding the dies 3, and in the worse casescenario eventually lead to breakage of said clamping tool 2. Due to thelarge forces and high torques involved in wrenching the pipes 11,breakage of any components can be both very dangerous and risk damageother parts of the system, for instance in case loose parts would getejected, hitting persons or materials, or if parts of the clamping tool2 would break loose and fall into the well bore.

For this reason a safety system and a corresponding safety arrangement 9is provided.

The safety system according to one embodiment of the invention will nowbe further described, referring mainly to FIGS. 2, 3A, 3B and 3C. InFIG. 2 the clamping tool 2 is seen from a perspective view, positionedsubstantially horizontally presenting a frontal pipe gripping portion104 provided with a slightly curved surface whereat there are arrangedsaid two dies 3. The clamping tool body 2 comprises at least one bore 8extending there through; in the appended figures the body of theclamping tool 2 comprises two horizontally extending through bores 8,8′. As seen in e.g. the cross section of FIG. 3B an elongated connectingelement 90, 90′ extends through each bore 8, 8′, and withholding means92, 92′ are coupled to the respective end portions 94, 94′ of saidconnecting element 90, 90′, in such a way that the connecting element 90is withheld or secured inside the bore 8, 8′. Thus the withholding means92 arranged at the end portions 94, 94′ of the connecting element 90couple the connecting element 90 to the clamping tool body 2 at twodifferent positions of the bore 8, wherein said positions are separatedfrom each other by a certain distance. In this context, the term“couple” used for describing the function of the withholding means 92,92′ means “to fasten in relation to”, i.e. that the withholding means92, 92′ are arranged to fasten the connecting element 90 in relation tothe clamping tool body 2 in such a way that the connecting element 90cannot be removed from the tool body 2 unless either of the withholdingmeans 92, 92′ is removed. As seen in FIG. 3B the respective positionswhereat the withholding means 92, 92′ couple the connecting means 90,90′ to the clamping tool body 2 are separated from each other by asubstantial portion of the clamping tool body 2, meaning that at least50% of the clamping tool body 2 separates the coupling positions. Apossible crack in the clamping tool body 2 will most likely develop inbetween said two coupling positions and thus in the event of breakage ofthe clamping tool body 2 any loose parts are still retained/heldtogether by the connecting element.

In one embodiment said bore 8, 8′ is a through bore having a first 83and a second 84 opening and extending through the solid body of theclamping tool 2,as is illustrated in the cross section in FIG. 3B. Thereference numbers for said first 83 and second 84 openings are shownonly for the uppermost through bore 8, however the skilled personunderstands that also the lowermost bore 8′ comprises correspondingfirst and second openings. At each of the first 83 and second 84openings the bore 8 comprises two outer first portions 80 with a firstdiameter D. In between two outer portions 80 the bore 8 furthercomprises a middle second portion 82 with a second diameter d. The firstdiameter D is larger than the second diameter d and the outer portions80 and the middle portion 82 of the bore 8 are connected by an flange 81corresponding to the position of the bore whereat the diameter of thebore 8 is shifted. As a non-limiting example the first diameter D isbetween 10-20 mm, preferably between 13-17 mm, and the second diameter dis between 4-12 mm, preferably between 6-10 mm.

The elongated connecting element 90, 90′ may for instance be a bar or awire or any other suitable element which provides the required materialstrength and shape. In the figures, the connecting element 90, 90′ isshown in the form of a solid bar having a circular cross section. Thediameter of the bar is dimensioned to fit in the middle portion 82 ofthe bore. In one non-limiting example the bar 90, 90′ has a diameter of7 mm.

As a non-limiting example the solid bar 90, 90′ can be made of a highstrength steel, such as a high strength low-alloy structural steel. Forinstance the bar can be made of steel S355 (complying with Europeanstandard EN 10025) having a proof strength R_(p0.2) of at least 520N/mm2 and a tensile strength between 630-950 N/mm2.

Said withholding means 92, 92′ are coupled to the respective endportions 94, 94′ of the connecting element 90, 90′. The withholdingmeans 92, 92′ may for instance be a securing component such as a nut, asis illustrated in the figures. A securing component 92, 92′ providesadvantages related to assembly of the system in that the connectingelement may firstly be inserted into the bore 8 whereafter the securingcomponent is attached to the respective end portion of the connectingelement e.g. by screwing thereby locking the connecting means intoposition. However the withholding means is not restricted to a nutcomponent and many other types of components fulfilling the samefunction may be used, such as rivets, nail heads or any stopper or othersecuring element which can be coupled to the connecting element andlock/hold it in position inside the bore 8, 8′. The withholding means 92has a body comprising at least one cross-section X (see FIG. 3C) whichis larger than the diameter d of the middle second portion 82 of thebore 8. In one embodiment one withholding means 92 is fitted in each ofthe two outer first portions 80 meaning that the withholding means aredimensioned to fit in the bore portions 80 having the diameter D.Moreover, the withholding means 92 are arranged in such a way that theirsize prevents them from entering the middle portion 82 of the bore 8. Inone example the withholding means in FIG. 3C is a nut with an outerdiameter X. The diameter X is dimensioned so that the nut can beinserted into the first portion 80 of the bore 8 but is prevented frompassing the flange 81 into the second portion 82 of the bore. Thus bycoupling one nut 92 to each end portion 94 of the correspondingconnecting element 90 the connecting element 90 is secured inside thethrough bore 8, and thereby the withholding means 92, 92′ couple theconnecting element to the clamping tool body 2. The withholding means 92can be coupled to the connecting element 90 in various ways. Forinstance in the embodiment where the withholding means 92 is a nut andthe connecting element is a bar, the nuts may be coupled to the endportions 94 of the bar by means of screwing, in which case the nut andthe bar are preferably arranged with complementary inner and outerthreads. However, the skilled person understands that other ways ofcoupling the withholding means 92 to the connecting element 90 are alsoconceivable, i.e. such as welding. The withholding means 92 are arrangedto couple the connecting element 90 to the clamping tool body 2 at twodifferent positions of the bore 8 which are separated from each other.In one example this means that one withholding means 92 is coupled toeach end portion 94 of the connecting element 90 at said outer firstportions 80 of the bore 8. In this example the two positions whereat therespective withholding means 92 couple the elongated connecting element90 to the clamping tool body 2 are separated by a substantial portion ofthe body of the clamping tool 2, preferably a majority (>50%) of thebody of the clamping tool 2.

One function of the nut 92 is to keep the connecting element 90 (i.e.the bar) in place inside the bore 8, but at the same time the bar 90also holds the nut 92 in position meaning the nut 90 and the bar 90cooperate in keeping the safety arrangement 9 in place.

FIG. 3A shows a side view of the clamping tool 2 with two horizontallyextending connecting elements 90, 90′ wherein each connecting elementextends between bore openings 83, 84 at the respective vertical sideportions of the tool body 2. The view in FIG. 3A shows one of the boreopenings 84. Herein it is seen that said two through bores 8, 8′ arearranged at different positions through the body 2 having differentalignments, both at different vertical locations and differenthorizontal locations, meaning that the clamping tool 2 is arranged withan uppermost 8 and a lowermost 8′ bore, as well as with a frontal 8′ anda rear 8 bore. Like positioning of the bores 8, 8′ may be advantageousfor safeguarding that at least one of the connecting element 90, 90′will be able to retain broken loose parts of the clamping tool 2 in caseof cracking of the tool body 2. However, it is evident that sometimesonly one through bore 8 and safety arrangement may be sufficient.

The safety system according to one embodiment of the invention furthercomprises at least one shock absorbing component 91 preferably arrangedat one of the outer first portions 80 of the bore 8 and adjacent to thewithholding means 92. Preferably the safety system is arranged with oneshock absorbing component 91 at each outer portion 80 of the bore 8, forinstance in FIG. 3B it is seen that two shock absorbing components 91are provided for each through bore 8: one at each outer portion 80 saidthrough bore 8.

The position of the shock absorbing component 91 is shown in theenlarged cross section of FIG. 3C. In a preferred aspect of theinvention the shock absorbing component 91 is designed as a casingembracing at least a part of the portion of the connecting element 90(i.e. the bar) located at said outer first bore portion 80. Preferablythe shock absorbing component 91 is dimensioned so that one end portionthereof abuts said flange 81 and another opposite end portion abuts thewithholding means 92 leading to that the shock absorbing component 91 inone embodiment essentially fills the space which is defined by the outerfirst portion 80, the flange 81 and the side of the withholding means 92which is facing the inside of the bore 8. In a preferred embodiment thewithholding means 92 is arranged/dimensioned so that, when thewithholding means 92 is coupled to the elongated connecting element 90and placed inside the bore 8, a passage or opening 93 is created betweenthe respective outer first portion 80 and the atmosphere outside thebore 8 at the outside of the clamping tool 2. Such a passage 93 may beachieved in that the withholding means in the form of a nut 92 isarranged with an indentation 93 or in that the diameter of the nut ismade smaller than the diameter of the outer first bore portion 80 sothat an annular opening is created between the outer circumference ofthe nut 92 and the inner walls of the respective outer first boreportion 80 when the nut is in position inside the bore 8. The functionof the passage 93 will be described in more detail in connection toFIGS. 6A-6B.

The shock absorbing component 91 is arranged to at least partiallyabsorb the energy generated upon burst of the tool 2. Such shockabsorbing property may be achieved in many ways. For instance the shockabsorbing component can be made of a shock absorbing material such asfor instance plastic, rubber, silicone, metal, ethyl cellulose basedmaterial or clay based material able to absorb and/or dampen shock uponimpact. Another way of achieving a shock absorbing property is toprovide a component having a certain shape/design such as e.g. acompression spring made of metal.

In one embodiment the shock absorbing component is made of a deformablematerial. It is to be understood that “deformable” herein may refer tothe property of altering the shape upon impact, either reversibly ornon-reversibly. A reversibly deformable material may for instance becompressible and/or elastic. A non-reversibly deformable material mayfor instance be pliable and/or foldable.

As an example the shock absorbing element 91 is made of an elasticmaterial such as rubber which is able to be compressed upon impactthereby absorbing shock caused by bursting and subsequently retake itsoriginal shape.

As another example the shock absorbing component 91 is a deformablecomponent made of a flexible modeling compound which can benon-reversibly deformed upon impact.

As yet another example the shock absorbing component 91 is made of aethyl cellulose based material, sometimes also comprising mineral oil.The shock absorbing component 91, e.g. a casing, may be drop-forged fromsaid ethyl cellulose material into a desired shape with desireddimensions, thus being given the shape i.e. of a casing. The shockabsorbing component 91 may also be die-cast from melted ethyl cellulosematerial into casings. Such material is non-reversibly deformable uponimpact.

FIG. 4 shows a detailed view of an energy absorbing arrangement 9according to one embodiment of the invention. The energy absorbingarrangement 9 is suitable for use in a safety system according to theinvention. The energy absorbing arrangement 9 comprises an elongatedconnecting element 90 which at each end portion 94 is coupled to awithholding means 92, and further a shock absorbing component 91 isarranged adjacent to each of said withholding means 92 at saidrespective end portions 94 of the connecting element. Each of therespective shock absorbing components 91 is arranged at the side of thecorresponding withholding means 92 which is facing the other oppositeend portion of the connecting element 90. The embodiment shown in FIG. 4comprises a connecting element in the form of a solid bar 90, twowithholding means in the form of nuts 92 and adjacent each nut 92 isarranged shock absorbing components in the form of deformable casings91.

The casings 91 (shock absorbing components 91) are arranged in such away that they at least partially embraces said solid bar. The casings 91are intended to function as energy absorbing elements in case ofbreakage of a clamping tool 2. Each end portion of the bar 90 is coupledto said withholding means 92, herein shown as a nut 92, which can befastened to the bar 90 e.g. by means of screwing.

FIG. 5 shows a planar view of an example of a withholding means 92 inthe form of a nut providing a securing function. The nut has a bodywhich comprises at least one cross-section X (herein corresponding tothe largest diameter of the essentially circular nut) which is largerthan the diameter d of said second portion 82 of the bore 8. The nutcomprises at least one indentation 93 which will later be described morethoroughly. In FIG. 5 the nut comprises two concave indentations 93symmetrically arranged around the circumference of the nut 92. When thenut 92 is coupled to an end portion of the bar 90 and the bar ispositioned inside the through bore 8 said indentation 93 creates anopening or a passage between the outer bore portion 80 and the outsideof the tool 2.

The function of the safety system, as well as of the correspondingsafety arrangement, will now be described in more detail, referringmainly to FIGS. 6A-B and 7A-B respectively which schematicallyillustrates a broken clamping tool 2 which has a crack 200 splitting thetool 2 into two loose portions. Herein the crack 200 extends verticallythrough the clamping tool 2 resulting in that the body 2 is divided intoa leftmost and a rightmost loose portion.

When a clamping tool 2 is subjected to mechanical stress, e.g. as aconsequence of gripping a pipe 11 with a diameter that does not matchthe curvature of the dies 3 used for gripping, it may happen that thebody of the tool 2 cracks apart. At the point when cracking/breakingoccurs there is a risk that the tool 2 will burst apart suddenly andviolently. Thanks to the safety system and safety arrangement retainingthe resulting loose portions, a situation where parts of the clampingtool 2 are ejected into different directions and potentially would causedamage to surrounding individuals and/or equipment is prevented. Theconnecting element/s 90, 90′ will function as a connector retaining theloose parts of the clamping tool 2. Furthermore, the shock absorbingcomponent 91 will act as a shock/energy absorber during the burst andwill efficiently dampen/absorb at least part of the kinetic energygenerated during breakage. The presence of the shock absorbingcomponents 91, 91′ also leads to that the withholding elements 92, 92′and the connecting means 90, 90′ are spared from at least a portion ofthe force generated during breakage of the tool 2 which further reducesthe already very small risk that coupling between i.e. the nuts 92 andthe bar 90 would also break.

The shock absorbing function of the shock absorbing element 91 is now tobe further described. In one embodiment the shock absorbing component 91is made of a casing in deformable material, for instance plastic basedmaterial. Bursting of a clamping tool 2 may lead to that loose partswill violently and suddenly split apart where said loose portions willmove in high speed into different directions. This movement causes theshock absorbing component 91, which is positioned at the outer boreportion 80 adjacent to the nut 92, to be squeezed between said boreflange 81 and said nut 92. When this occurs the shock absorbingcomponent 91 is deformed thus absorbing kinetic energy generated at theburst.

In one embodiment the withholding means 92 is arranged with a passage 93connecting the outer bore portion 80 with the atmosphere outside of theclamping tool 2. The function of said passage 93 is now to be furtherdescribed.

In the following example the shock absorbing component 91 is made of adeformable material. One example of a passage 93 is created bysymmetrically arranged indentations 93 in the nut 92, seen in FIG. 5,but other ways of creating a passage are of course also conceivable.Presence of such a passage 93 allows for a portion of the deformableshock absorbing component 91 to exit the bore 8 during breakage of theclamping tool 2 which contributes to the cushioning effect. For examplein FIG. 6B and FIG. 7B respectively there is illustrated a situationafter breakage of the tool 2 where a portion of the shock absorbingcomponent 91, 91′ has exit the bore 8 due to squeezing during breakage.

At bursting of the clamping tool 2 the shock absorbing component 91 issqueezed between the flange 81 and the nut 92 resulting in that aportion thereof will pass through the passage 93 between the nut 92 andthe corresponding inner wall of the outer first bore portion 80. Inother words, the nut will stop a part of the material of the shockabsorbing component 91 from exiting the bore, while the passage 93 willallow for a restricted portion to pass. Said passage 93 will herebyprovide a choking effect and a shock absorbing effect is achieved whichdampens the kinetic forces generated upon the burst.

As is previously described a passage 93 between the body of thewithholding means 92 and the inner wall of the outer first bore portion80 can be created in many ways, for instance as an annular passagebetween the outer circumference of a nut and the inner wall of said bore8.

Altering the area of the passage 93 in relation to the area of thewithholding means 92 will also alter the choking effect and also theshock absorption, i.e. the energy absorption. Also the mass or volume ofthe shock absorbing component 91 will affect the energy absorption whichin its turn is dependent on the size/dimension of the outer first boreportion 80 whereat the shock absorbing component is arranged to befitted. Thus, when adapting the system for being able to provide acertain dampening, the mass and volume of the shock absorbing component91 is balanced against the area of the passage 93 and the (blocking)area of the withholding means 92.

Also the physical properties of the shock absorbing component 91 mayaffect the outline of the system. Increase viscosity of the material mayrequire smaller passage and vice versa.

The “area of the passage” is to be interpreted as the difference betweenthe cross area of the opening of the outer first bore portion 80 and thearea of the withholding means 92 arranged to block the bore hole opening84.

As one non-limiting example of dimensions the diameter of the bore holeopening 84 is 15 mm leading to a cross sectional area of around 177 mm2.The blocking area of the nut is around 122 mm2 and the total area of thepassage 93 is thus around 55 mm2. The shock absorbing component 91 ismade of an ethyl cellulose based material and has a essentiallycylindrical shape with a diameter of 15 mm and a length of 20 mmresulting in a volume of around 3500 mm3.

The skilled person understands that the energy absorbing property of theshock absorbing component 91 can be achieved in different ways and thatit can be made of various materials as well as having various shapes.For instance the shock absorbing component 91 may be an elastic casingmade of rubber or silicone, or it may be a pliable, plastic basedmaterial which is injected into the bore 8 prior to/after fastening thenut 92 to the bar 90.

It is understood that the objects of the present invention set forthabove, among those made apparent by the detailed description, shall beinterpreted as illustrative and not in a limiting sense. Within thescope of the following claims the set-up of various alterations of thepresent invention may be possible.

For instance the connecting element can be a bar or a wire which ispositioned inside a through bore or within a groove created on the outersurface of the tool.

1.-12. (canceled)
 13. A safety system for a gripping device comprising:a clamping tool having a body; at least one bore through the body of theclamping tool; at least one elongated connecting element extendingthrough the bore; and withholding element arranged to couple theconnecting element to the clamping tool body at two different positionsof the bore separated from each other.
 14. The safety system accordingto claim 13, wherein the body of the clamping tool is a casted item witha single solid body preferably made of metal.
 15. The safety systemaccording to claim 14, wherein said bore is a through bore comprisingtwo outer first portions and a middle second portion located in betweensaid two outer first portions, where said outer first portions have adiameter which is larger than the diameter of the middle second portion,and further wherein the withholding element has a body which comprisesat least one cross-section which is larger than the diameter of themiddle second portion of the bore, where one withholding element ispositioned at each of the outer first portions of the through bore insuch a way that they are prevented from entering the middle secondportion of the bore.
 16. The safety system according to claim 15,wherein each of said withholding element is dimensioned so that when itis positioned inside the outer first portion a passage is createdbetween the outer first portion of the bore and the atmosphere outsidethe bore.
 17. The safety system according to claim 16, wherein saidwithholding element is in the form of a securing component arranged tobe coupled to end portions of the connecting element.
 18. The safetysystem according to claim 13, further comprising at least one shockabsorbing component arranged at an outer portion of the bore andadjacent to said withholding element.
 19. The safety system according toclaim 18, wherein said shock absorbing component is made of adeformable/pliable material.
 20. The safety system according to 13,wherein said elongated connecting element is a bar element made of steelmaterial.
 21. The safety system according to claim 1, wherein saidelongated connecting element is a wire element.
 22. The safety systemaccording to claim 1, wherein the safety system is configured for agripper for gripping a pipe.
 23. An energy absorbing arrangementcomprising: an elongated connecting element having at least two endportions; each end portion is coupled to a withholding element; and ashock absorbing component arranged adjacent to the withholding elementat each end portion of the elongated connecting element.
 24. A safetyarrangement for a gripping device comprising: a clamping tool having abody; at least one elongated connecting element coupled to the body by awithholding element at two different positions separated from eachother.